The present invention relates generally to systems and methods for performing chemical and biological analyses. More particularly, the present invention relates to the design and use of an analyzer system which employs analytical substrates evaluated in a modular interface structure having one or more interchangeable modules with varying functionality for interfacing with an arrangement of analytical and control systems instruments.
Numerous systems and instruments are available for performing chemical, clinical, and environmental analyses of chemical and biological specimens. Conventional systems may employ a variety of detection devices for monitoring a chemical or physical change which is related to the composition or other characteristic of the specimen being tested. Such instruments includes spectrophotometers, fluorometers, light detectors, radioactive counters, magnetometers galvanometers, reflectometers, ultrasonic detectors, temperature detectors, pressure detectors, mephlometers, electrophoretic detectors, PCR systems, LCR systems, and the like. Such instruments are often combined with electronic support systems, such as microprocessors, timers, video displays, LCD displays, input devices, output devices, and the like, in a stand-alone analyzer. Such analyzers may be adapted to receive a sample directly but will more usually be designed to receive a sample placed on a sample-receiving substrate such as a dipstick, cuvette, analytical rotor or the like. Usually, the sample-receiving substrate will be made for a single use (i.e., will be disposable), and the analyzer will include the circuitry, optics, sample manipulation, and other structure necessary for performing the assay on the substrate. As a result, most analyzers are intended to work only with a single type of sample-receiving substrate and are not readily adaptable to be used with other substrates.
Recently, a new class of sample-receiving substrate has been developed, referred to as “microfluidic” systems. Microfluidic substrates have networks of chambers connected by channels which have mesoscale dimensions, where at least one dimension is usually between 0.1 μm and 500 μm. Such microfluidic substrates may be fabricated using photolithographic techniques similar to those used in the semi-conductor industry, and the resulting devices can be used to perform a variety of sophisticated chemical and biological analytical techniques. Microfluidic analytical technology has a number of advantages, including the ability to use very small sample sizes, typically on the order of nanoliters. The substrates may be produced at a relatively low cost, and can be formatted to perform numerous specific analytical operations, including mixing, dispensing, valving, reactions, and detections.
Another recently developed class of sample-receiving microfluidic substrates includes substrates having a capillary interface that allows compounds to be brought onto the test substrate from an external source, and which can be advantageously used in a number of assay formats for high-throughput screening applications. These assay formats include fluorogenic assays, fluorescence polarization assays, non-fluorogenic mobility shift assays, dose response assays, and calcium flux cell-based assays.
Because of the variety of analytical techniques and potentially complex sample flow patterns that may be incorporated into particular microfluidic test substrates, significant demands may be placed on the analytical units which support the test substrates. The analytical units not only have to manage the direction and timing of flow through the network of channels and reservoirs on the substrate, they may also have to provide one or more physical interactions with the samples at locations distributed around the substrate, including heating, cooling, exposure to light or other radiation, detection of light or other radiation or other emissions, measuring electrical/electrochemical signals, pH, and the like. The flow control management may also comprise a variety of interactions, including the patterned application of voltage, current, or power to the substrate (for electrokinetic flow control), or the application of pressure, vacuum, acoustic energy or other mechanical interventions for otherwise inducing flow.
It can thus be seen that a virtually infinite number of specific test formats may be incorporated into microfluidic test substrates. Because of such variety and complexity, many if not most of the test substrates will require specifically configured analyzers in order to perform a particular test. It is indeed possible that particular test substrates use more than one analyzer for performing different tests. The need to provide one dedicated analyzer for every substrate and test, however, will significantly reduce the flexibility and cost advantages of the microfluidic systems. Additionally, for a specifically configured analyzer, test substrates are generally only useful for performing a limited number of assay formats and functions. As the complexity and costs of test substrates increase, it becomes more desirable to increase the number of useful assay formats and functions for a particular test substrate-analyzer combination, or for a particular class of substrates in combination with a specifically configured analyzer.
It would therefore be desirable to provide improved analytical systems and methods that overcome or substantially mitigate at least some of the problems set forth above. In particular, it would be desirable to provide analytical systems including a modular interface structure which can support a number of different microfluidic or other test substrates having substantially different flow patterns, chemistries, and other analytical characteristics. It would also be particularly desirable to provide analytical systems including a modular substrate-to-instrument interface structure comprised of interchangeable modules to accommodate various combinations of assay formats and functions, such as different flow patterns, for a particular test substrate or a particular class of test substrates having similar design layouts and/or properties. The costs for modifying the analytical and control systems interface as well as the costs required for obtaining test substrates for desired assays would be significantly reduced.